3263 lbs + 330lbs = 3593 lbs / 320hp = 11.23 lb/hp
WRX: assuming similar power to the STi.
3085 lbs / 276 hp = 11.18 lb/hp (.05 favorable vs the Porsche)
It may be pretty unrealistic to claim HP similar to the STi, since it is running exhaust improvements PLUS more boost, and other improvements. It might be safer to assume something closer to 250, (totally stock being 227) in which case:
3085 lbs / 250hp = 12.34 lb/hp (1.11 unfavorable vs the Porsche)
So, giving BobbyD the benefit of the doubt, I'd say this story is at least borderline plausable. He was, after all, running against a dentist. (hehe, just kidding, BobbyD)